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Shock fluid therapy basics

In his presentation, “Colloids: Changes in Use” during the 2013 Veterinary Emergency and Critical Care Society meeting, William Muir, DVM, MS, PhD, DACVA, DACVECC, reviewed the use of crystalloids and colloids for resuscitation and in the perioperative phase.

Dr. Muir reminded clinicians that “fluids are drugs” and of the importance of goal-directed fluid therapy. For most perioperative situations and for resuscitation requiring volume replacement, Plasma-Lyte A or R (Baxter), Normosol R or M (Hospira), and mildly alkalinizing balanced isotonic replacement crystalloid fluids, such as lactated Ringer’s solution, are good first choices for fluid therapy. Dr. Muir noted, however, that 0.9% sodium chloride should be used cautiously since it is an acidifying solution. The use of this crystalloid should be reserved for patients with profuse vomiting or small bowel diarrhea in which alkalemia is suspected. Use of full-strength saline solution in patients that are not alkalotic can worsen renal perfusion.

There is currently some discussion about the use of colloids such as hydroxyethyl starches (HES) in veterinary medicine because of concerns with renal injury. Negative outcomes involving HES use in human medicine have prompted removal of these products from the market in the U.K. In the United States, the FDA has issued a boxed warning for use of these products in human medicine and recommends that they be used cautiously in patients with critical illness or with a risk of renal injury. There is also concern about the use of these products in patients with head trauma or coagulopathy. These issues have not been documented in veterinary medicine, and there is no consensus on this issue at this time.

Dr. Muir discussed use of tetrastarches in veterinary medicine and noted that, in human trials, these have been associated with less risk of renal injury and may be a better option for some patients. An additional benefit of their use is their shorter half-life compared with other HES products, which would minimize patient risk in the event of a complication.